A passenger vehicle may include a heat pump for cooling and/or heating the vehicle's cabin. The heat pump may include an outside heat exchanger that acts as an evaporator during passenger cabin heating and as a condenser during passenger cabin cooling. However, during passenger cabin heating, evaporator fins may experience freezing or icing. If the fins freeze and ice forms on the fins, the heat pump heating efficiency may be reduced. Consequently, it may be desirable to determine if evaporator fins may be freezing. However, evaporator fins may freeze differently during different operating conditions. For example, during one operating condition, the evaporator fins may begin to freeze in response to a first condition, and during a second operating condition, the fins may begin to freeze in response to a second condition. Therefore, it may be a challenge to determine when the evaporator fins will begin to freeze so that mitigating actions may be taken.
The inventor herein has recognized the above-mentioned disadvantages for operating an evaporator and has developed a method for operating a vehicle climate control system, comprising: adjusting a temperature threshold in response to a position of grille shutters; judging whether or not evaporator fins are expected to freeze in response to the position of grille shutters; and performing an action to reduce a possibility of the evaporator fins freezing.
By performing an action in response to a comparison of evaporator fin temperature and a temperature threshold that varies with vehicle operating conditions, it may be possible to provide the technical result of reducing the possibility of evaporator fin freezing. The action may include adjusting a position of grille shutters, adjusting expansion valve state, entering a different heat pump operating mode, or other mitigating action. In this way, different vehicle conditions may be incorporated into a way of determining the possibility of evaporator fin freezing so that evaporator fin freezing may be avoided.
The present description may provide several advantages. Specifically, the approach may improve heat pump efficiency during some operating conditions. Further, the approach may reduce the possibility of evaporator fin freezing. Additionally, the approach may improve passenger comfort in a vehicle's passenger cabin.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.